Business Combinations - Narrative (Details) - USD ($)				3 Months Ended		6 Months Ended
	Jul. 26, 2019	May 18, 2018	Apr. 29, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Payments of consent fees				$ 0	$ 38,000,000	$ 0	$ 38,000,000
DISH | Subsequent Event | T-Mobile and Sprint | Prepaid Business
Business Acquisition [Line Items]
Payments for asset acquisition	$ 1,400,000,000
DISH | Subsequent Event | T-Mobile and Sprint | Prepaid Business | Transition Services Agreement
Business Acquisition [Line Items]
Transition period (up to)	3 years
DISH | Subsequent Event | T-Mobile and Sprint | Prepaid Business | Master Network Services Agreement
Business Acquisition [Line Items]
Transition period (up to)	7 years
DISH | Subsequent Event | T-Mobile and Sprint | Spectrum Licenses
Business Acquisition [Line Items]
Payments for asset acquisition	$ 3,600,000,000
Additional lease period	2 years
T-Mobile and Sprint | Subsequent Event | DISH | Decommissioned Towers and Retail Locations
Business Acquisition [Line Items]
Option period (up to)	5 years
Sprint
Business Acquisition [Line Items]
Exchange ratio			0.10256
Exchange ratio (in shares)			9.75
Fully-diluted shares of combined company held by public stockholders (percent)								30.90%
Required fees by acquirer upon consummation				0		0
Required reimbursement by acquiree upon termination, percentage		33.00%
Accrued required reimbursement by acquiree upon termination				0		0
Required reimbursement by acquirer upon termination, percentage		67.00%
Required reimbursement by acquirer upon termination		$ 162,000,000
Accrued required reimbursement by acquirer upon termination				0		0
Costs recognized associated with merger transaction				222,000,000	$ 41,000,000	335,000,000
Required payment resulting from failure to satisfy closing condition of business combination agreement (up to)			$ 600,000,000
Sprint | Senior Notes
Business Acquisition [Line Items]
Payments of consent fees		$ 14,000,000
Sprint | Secured Term Loan Facility
Business Acquisition [Line Items]
Financing commitment, amount				7,000,000,000		7,000,000,000
Sprint | Deutsche Telekom AG
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)								41.70%
Required fees by acquirer upon consummation				$ 0		$ 0
Sprint | SoftBank
Business Acquisition [Line Items]
Fully-diluted shares expected to be held immediately following merger (percent)								27.40%